<?php
/**
 * CMysqlSchema class file.
 *
 * @author Qiang Xue <qiang.xue@gmail.com>
 * @link http://www.yiiframework.com/
 * @copyright 2008-2013 Yii Software LLC
 * @license http://www.yiiframework.com/license/
 */

/**
 * CMysqlSchema is the class for retrieving metadata information from a MySQL database (version 4.1.x and 5.x).
 *
 * @author Qiang Xue <qiang.xue@gmail.com>
 * @package system.db.schema.mysql
 * @since 1.0
 */
class CMysqlSchema extends CDbSchema
{
    /**
     * @var array the abstract column types mapped to physical column types.
     * @since 1.1.6
     */
    public $columnTypes = array(
        'pk' => 'int(11) NOT NULL AUTO_INCREMENT PRIMARY KEY',
        'string' => 'varchar(255)',
        'text' => 'text',
        'integer' => 'int(11)',
        'float' => 'float',
        'decimal' => 'decimal',
        'datetime' => 'datetime',
        'timestamp' => 'timestamp',
        'time' => 'time',
        'date' => 'date',
        'binary' => 'blob',
        'boolean' => 'tinyint(1)',
        'money' => 'decimal(19,4)',
    );

    /**
     * Quotes a table name for use in a query.
     * A simple table name does not schema prefix.
     * @param string $name table name
     * @return string the properly quoted table name
     * @since 1.1.6
     */
    public function quoteSimpleTableName($name)
    {
        return '`' . $name . '`';
    }

    /**
     * Quotes a column name for use in a query.
     * A simple column name does not contain prefix.
     * @param string $name column name
     * @return string the properly quoted column name
     * @since 1.1.6
     */
    public function quoteSimpleColumnName($name)
    {
        return '`' . $name . '`';
    }

    /**
     * Compares two table names.
     * The table names can be either quoted or unquoted. This method
     * will consider both cases.
     * @param string $name1 table name 1
     * @param string $name2 table name 2
     * @return boolean whether the two table names refer to the same table.
     */
    public function compareTableNames($name1, $name2)
    {
        return parent::compareTableNames(strtolower($name1), strtolower($name2));
    }

    /**
     * Resets the sequence value of a table's primary key.
     * The sequence will be reset such that the primary key of the next new row inserted
     * will have the specified value or max value of a primary key plus one (i.e. sequence trimming).
     * @param CDbTableSchema $table the table schema whose primary key sequence will be reset
     * @param integer|null $value the value for the primary key of the next new row inserted.
     * If this is not set, the next new row's primary key will have the max value of a primary
     * key plus one (i.e. sequence trimming).
     * @since 1.1
     */
    public function resetSequence($table, $value = null)
    {
        if ($table->sequenceName === null)
            return;
        if ($value !== null)
            $value = (int)$value;
        else {
            $value = (int)$this->getDbConnection()
                ->createCommand("SELECT MAX(`{$table->primaryKey}`) FROM {$table->rawName}")
                ->queryScalar();
            $value++;
        }
        $this->getDbConnection()
            ->createCommand("ALTER TABLE {$table->rawName} AUTO_INCREMENT=$value")
            ->execute();
    }

    /**
     * Enables or disables integrity check.
     * @param boolean $check whether to turn on or off the integrity check.
     * @param string $schema the schema of the tables. Defaults to empty string, meaning the current or default schema.
     * @since 1.1
     */
    public function checkIntegrity($check = true, $schema = '')
    {
        $this->getDbConnection()->createCommand('SET FOREIGN_KEY_CHECKS=' . ($check ? 1 : 0))->execute();
    }

    /**
     * Loads the metadata for the specified table.
     * @param string $name table name
     * @return CMysqlTableSchema driver dependent table metadata. Null if the table does not exist.
     */
    protected function loadTable($name)
    {
        $table = new CMysqlTableSchema;
        $this->resolveTableNames($table, $name);

        if ($this->findColumns($table)) {
            $this->findConstraints($table);
            return $table;
        } else
            return null;
    }

    /**
     * Generates various kinds of table names.
     * @param CMysqlTableSchema $table the table instance
     * @param string $name the unquoted table name
     */
    protected function resolveTableNames($table, $name)
    {
        $parts = explode('.', str_replace(array('`', '"'), '', $name));
        if (isset($parts[1])) {
            $table->schemaName = $parts[0];
            $table->name = $parts[1];
            $table->rawName = $this->quoteTableName($table->schemaName) . '.' . $this->quoteTableName($table->name);
        } else {
            $table->name = $parts[0];
            $table->rawName = $this->quoteTableName($table->name);
        }
    }

    /**
     * Collects the table column metadata.
     * @param CMysqlTableSchema $table the table metadata
     * @return boolean whether the table exists in the database
     */
    protected function findColumns($table)
    {
        $sql = 'SHOW FULL COLUMNS FROM ' . $table->rawName;
        try {
            $columns = $this->getDbConnection()->createCommand($sql)->queryAll();
        } catch (Exception $e) {
            return false;
        }
        foreach ($columns as $column) {
            $c = $this->createColumn($column);
            $table->columns[$c->name] = $c;
            if ($c->isPrimaryKey) {
                if ($table->primaryKey === null)
                    $table->primaryKey = $c->name;
                elseif (is_string($table->primaryKey))
                    $table->primaryKey = array($table->primaryKey, $c->name);
                else
                    $table->primaryKey[] = $c->name;
                if ($c->autoIncrement)
                    $table->sequenceName = '';
            }
        }
        return true;
    }

    /**
     * Creates a table column.
     * @param array $column column metadata
     * @return CDbColumnSchema normalized column metadata
     */
    protected function createColumn($column)
    {
        $c = new CMysqlColumnSchema;
        $c->name = $column['Field'];
        $c->rawName = $this->quoteColumnName($c->name);
        $c->allowNull = $column['Null'] === 'YES';
        $c->isPrimaryKey = strpos($column['Key'], 'PRI') !== false;
        $c->isForeignKey = false;
        $c->init($column['Type'], $column['Default']);
        $c->autoIncrement = strpos(strtolower($column['Extra']), 'auto_increment') !== false;
        if (isset($column['Comment']))
            $c->comment = $column['Comment'];

        return $c;
    }

    /**
     * @return float server version.
     */
    protected function getServerVersion()
    {
        $version = $this->getDbConnection()->getAttribute(PDO::ATTR_SERVER_VERSION);
        $digits = array();
        preg_match('/(\d+)\.(\d+)\.(\d+)/', $version, $digits);
        return floatval($digits[1] . '.' . $digits[2] . $digits[3]);
    }

    /**
     * Collects the foreign key column details for the given table.
     * @param CMysqlTableSchema $table the table metadata
     */
    protected function findConstraints($table)
    {
        $row = $this->getDbConnection()->createCommand('SHOW CREATE TABLE ' . $table->rawName)->queryRow();
        $matches = array();
        $regexp = '/FOREIGN KEY\s+\(([^\)]+)\)\s+REFERENCES\s+([^\(^\s]+)\s*\(([^\)]+)\)/mi';
        foreach ($row as $sql) {
            if (preg_match_all($regexp, $sql, $matches, PREG_SET_ORDER))
                break;
        }
        foreach ($matches as $match) {
            $keys = array_map('trim', explode(',', str_replace(array('`', '"'), '', $match[1])));
            $fks = array_map('trim', explode(',', str_replace(array('`', '"'), '', $match[3])));
            foreach ($keys as $k => $name) {
                $table->foreignKeys[$name] = array(str_replace(array('`', '"'), '', $match[2]), $fks[$k]);
                if (isset($table->columns[$name]))
                    $table->columns[$name]->isForeignKey = true;
            }
        }
    }

    /**
     * Returns all table names in the database.
     * @param string $schema the schema of the tables. Defaults to empty string, meaning the current or default schema.
     * If not empty, the returned table names will be prefixed with the schema name.
     * @return array all table names in the database.
     */
    protected function findTableNames($schema = '')
    {
        if ($schema === '')
            return $this->getDbConnection()->createCommand('SHOW TABLES')->queryColumn();
        $names = $this->getDbConnection()->createCommand('SHOW TABLES FROM ' . $this->quoteTableName($schema))->queryColumn();
        foreach ($names as &$name)
            $name = $schema . '.' . $name;
        return $names;
    }

    /**
     * Creates a command builder for the database.
     * This method overrides parent implementation in order to create a MySQL specific command builder
     * @return CDbCommandBuilder command builder instance
     * @since 1.1.13
     */
    protected function createCommandBuilder()
    {
        return new CMysqlCommandBuilder($this);
    }

    /**
     * Builds a SQL statement for renaming a column.
     * @param string $table the table whose column is to be renamed. The name will be properly quoted by the method.
     * @param string $name the old name of the column. The name will be properly quoted by the method.
     * @param string $newName the new name of the column. The name will be properly quoted by the method.
     * @throws CDbException if specified column is not found in given table
     * @return string the SQL statement for renaming a DB column.
     * @since 1.1.6
     */
    public function renameColumn($table, $name, $newName)
    {
        $db = $this->getDbConnection();
        $row = $db->createCommand('SHOW CREATE TABLE ' . $db->quoteTableName($table))->queryRow();
        if ($row === false)
            throw new CDbException(Yii::t('yii', 'Unable to find "{column}" in table "{table}".', array('{column}' => $name, '{table}' => $table)));
        if (isset($row['Create Table']))
            $sql = $row['Create Table'];
        else {
            $row = array_values($row);
            $sql = $row[1];
        }
        if (preg_match_all('/^\s*[`"](.*?)[`"]\s+(.*?),?$/m', $sql, $matches)) {
            foreach ($matches[1] as $i => $c) {
                if ($c === $name) {
                    return "ALTER TABLE " . $db->quoteTableName($table)
                    . " CHANGE " . $db->quoteColumnName($name)
                    . ' ' . $db->quoteColumnName($newName) . ' ' . $matches[2][$i];
                }
            }
        }

        // try to give back a SQL anyway
        return "ALTER TABLE " . $db->quoteTableName($table)
        . " CHANGE " . $db->quoteColumnName($name) . ' ' . $newName;
    }

    /**
     * Builds a SQL statement for dropping a foreign key constraint.
     * @param string $name the name of the foreign key constraint to be dropped. The name will be properly quoted by the method.
     * @param string $table the table whose foreign is to be dropped. The name will be properly quoted by the method.
     * @return string the SQL statement for dropping a foreign key constraint.
     * @since 1.1.6
     */
    public function dropForeignKey($name, $table)
    {
        return 'ALTER TABLE ' . $this->quoteTableName($table)
        . ' DROP FOREIGN KEY ' . $this->quoteColumnName($name);
    }


    /**
     * Builds a SQL statement for removing a primary key constraint to an existing table.
     * @param string $name the name of the primary key constraint to be removed.
     * @param string $table the table that the primary key constraint will be removed from.
     * @return string the SQL statement for removing a primary key constraint from an existing table.
     * @since 1.1.13
     */
    public function dropPrimaryKey($name, $table)
    {
        return 'ALTER TABLE ' . $this->quoteTableName($table) . ' DROP PRIMARY KEY';

    }

    /**
     * Builds a SQL statement for adding a primary key constraint to a table.
     * @param string $name not used in the MySQL syntax, the primary key is always called PRIMARY and is reserved.
     * @param string $table the table that the primary key constraint will be added to.
     * @param string|array $columns comma separated string or array of columns that the primary key will consist of.
     * @return string the SQL statement for adding a primary key constraint to an existing table.
     * @since 1.1.14
     */
    public function addPrimaryKey($name, $table, $columns)
    {
        if (is_string($columns))
            $columns = preg_split('/\s*,\s*/', $columns, -1, PREG_SPLIT_NO_EMPTY);
        foreach ($columns as $i => $col)
            $columns[$i] = $this->quoteColumnName($col);
        return 'ALTER TABLE ' . $this->quoteTableName($table) . ' ADD PRIMARY KEY ('
        . implode(', ', $columns) . ' )';
    }
}
